煤层气双重整制合成气新型载Ni-MCx催化剂活性组分协同作用和载体效应研究

Coal seam gas is one kind of abundant resource associated with coal, and it’s simultaneously considered as an important greenhouse gas. Methane, as the principal component of coal seam gas, will be used as a model molecule, this proposal focused on the combined CO2-H2O reforming of methane (CRM) to produce synthesis gas is great dual significance for both resource and environment protection. Due to the poor-availability and high cost of precious metals, to replace precious metals with non-precious ones is a promising approach. Nickel-based catalysts have been excessively employed for CRM reforming of methane, and they have exhibited high catalytic activity and selectivity, but the coke- and metal sintering-resistance stability remains to be further improved. Our previous studies demonstrate that the introduction of Mo2C into the supported Ni catalyst on zirconia improved the catalytic stability for CRM reaction. The proposed work is, based on the previous work, to study the fabrication of the novel supported Ni-MCx (M is Mo or W) catalysts on nano-structured zirconia carriers (nanobelt and nanowire, etc) and the catalytic performance in CRM reaction. The purpose is to improve the catalytic stability of existing Ni based catalysts in CRM reaction through the tuning of the M type, M/Ni ratio, Ni-MCx loading and reduction-carburization parameters, and as well as the controllable fabrication of the modified nano-structured zirconia. Moreover, this proposed research is also devoted to reveal the rule of active-component synergism and the support effect in CRM for synthesis gas production through correlating the nature of fresh and spent catalysts to catalytic performance in CRM reaction. The main objective for the proposed research is to provide some academic guidance for the clean and highly efficient utilization of the abundant resource of associated gas with coal in China.

煤层气是储量十分丰富的煤炭伴生资源，也是重要温室气体。拟以煤层气主要成分甲烷为模型分子，研究其CO2-H2O双重整以制取合成气，具有资源和环境双重意义。鉴于贵金属储量低、价格高的缺陷，非贵金属颇具前景。后者主要集中于Ni，展示出了与贵金属可比的催化活性和选择性，但其抗积碳、抗烧结稳定性亟待提高。申请者发现，Mo2C的引入能够改善Ni/ZrO2的稳定性。本项目拟研究新颖纳米结构氧化锆（纳米带、纳米网等）载Ni-MCx（M为Mo或W）催化甲烷CO2-H2O双重整，通过M种类、M/Ni比、载量和碳化参数的调变和掺杂改性的新颖纳米结构氧化锆的构筑，以提升Ni基催化剂的催化稳定性。通过对甲烷CO2-H2O双重整反应数据的分析并结合新鲜和失活催化剂的表征，揭示所构筑的新颖载Ni-MCx催化剂活性组分协同作用的规律和载体效应。本项目旨在为我国煤层气这一丰富煤炭伴生资源的高效、清洁资源化利用提供科学依据。

煤层气是储量十分丰富的煤炭伴生资源，也是重要温室气体。以煤层气主要成分甲烷为模型分子，研究其重整反应来制取合成气，具有资源和环境双重意义。本项目针对现有镍基催化剂稳定性不够理想的问题，开展了镍-碳化钼协同作用及担载镍基催化剂的载体效应研究。发现适量碳化钼的引入可以有效促进镍基催化剂的催化性能，加强镍与载体的相互作用，从而抑制镍的烧结并改变积碳类型，在载镍-碳化钼催化剂上形成须状积碳，而在非改性的载镍催化剂上形成壳状碳。须状碳并不降低活性位可及性，因此，表现出优良的稳定性。通过碳化钼改性载镍催化剂的制备、表征、催化性能和构效关系研究，揭示了镍-碳化钼协同作用的规律和机制。制备金属镍的精氨酸、乌洛托品络合物，以此作为浸渍剂，研究了配体辅助浸渍法制备的载镍催化剂的甲烷重整催化性能和构效关系，发现配体辅助浸渍可以提高镍分散性和可还原性，产生氧空穴，加强镍与载体的相互作用，提高催化剂的甲烷重整催化活性。强的金属-载体相互作用在提高金属镍抗烧结性能的同时，还可以改变积碳类型，提高催化剂的稳定性。载体的形貌和结构对载镍催化剂的物化性质和催化性能影响显著，采用不同的制备方法和制备参数，构筑了系列不同结构和形貌的氧化锆载体，构建了具有不同组成、结构、形貌和物化性质的氧化锆载镍基催化剂，通过TEM、FESEM、XRD、BET、Raman、TPD、化学吸附、XPS、TGA、TPH等表征手段对载体及反应前后催化剂进行分析和表征，关联甲烷重整催化性能测试结果，研究了所构建的催化剂的构效关系、载体效应及调控的规律和机制。通过多种表征手段对构筑的镍基纳米簇催化剂进行表征，理清了催化剂的特征与甲烷重整催化反应性能之间的关系，基本阐明了所设计催化剂好的甲烷重整催化性能的原因和机理。此外，还开展了纳米碳材料的制备与调控研究。纳米碳可以作为硬模板来制备新形貌催化剂，这为后续开展新结构高性能甲烷重整催化剂的研究奠定基础。总的来讲，通过本项目研究，制备了具有高的活性和稳定性的催化剂，并发现了一些有价值的规律。镍基催化剂价格较低、性能较好，用于甲烷重整制合成气潜力巨大、前景看好。但是，其催化稳定性仍有待进一步提高。本项目的研究成果，对高稳定的镍基甲烷重整催化剂的开发具有一定借鉴意义。